Menu closes when reaching separator line in sub menus

Opera's main menu disappears when I reach a separator line in a sub menu. The reason is that I use one single click to access menus. (Mouse down on the main menu -> move to designated menu -> release mouse button.)

To recreate: I press down the left mouse button on the main "Opera" menu, and while holding down the left mouse button I move down to e.g. "Page", move out to the sub menu, and when I reach the separator line just above the "Encoding" entry, the menu closes. Other windows applications do not do this (try e.g. mspaint or visual studio).

I know that I can avoid this by using 2 mouse clicks to access the menus, but I think this is a clumsy work-around, and I always forget because I usually access menus like this.

To recreate: I press down the left mouse button on the main "Opera" menu, and while holding down the left mouse button I move down to e.g. "Page", move out to the sub menu, and when I reach the separator line just above the "Encoding" entry, the menu closes. Other windows applications do not do this (try e.g. mspaint or visual studio).

It seems I didn't write down the bug number. I was probably expecting to be able to find the bug myself in the bug tracking system afterwards. But it was filed under my chopchip user, so maybe it's possible to locate it that way around?